Hierarchical Stateful Path Computation Element (PCE)
RFC 8751
Internet Engineering Task Force (IETF) D. Dhody
Request for Comments: 8751 Huawei Technologies
Category: Informational Y. Lee
ISSN: 2070-1721 Samsung Electronics
D. Ceccarelli
Ericsson
J. Shin
SK Telecom
D. King
Lancaster University
March 2020
Hierarchical Stateful Path Computation Element (PCE)
Abstract
A stateful Path Computation Element (PCE) maintains information on
the current network state received from the Path Computation Clients
(PCCs), including computed Label Switched Paths (LSPs), reserved
resources within the network, and pending path computation requests.
This information may then be considered when computing the path for a
new traffic-engineered LSP or for any associated/dependent LSPs. The
path-computation response from a PCE helps the PCC to gracefully
establish the computed LSP.
The Hierarchical Path Computation Element (H-PCE) architecture allows
the optimum sequence of interconnected domains to be selected and
network policy to be applied if applicable, via the use of a
hierarchical relationship between PCEs.
Combining the capabilities of stateful PCE and the hierarchical PCE
would be advantageous. This document describes general
considerations and use cases for the deployment of stateful, but not
stateless, PCEs using the hierarchical PCE architecture.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are candidates for any level of Internet
Standard; see Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8751.
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Table of Contents
1. Introduction
1.1. Background
1.2. Use Cases and Applicability of Hierarchical Stateful PCE
1.2.1. Applicability to ACTN
1.2.2. End-to-End Contiguous LSP
1.2.3. Applicability of a Stateful P-PCE
2. Terminology
2.1. Requirements Language
3. Hierarchical Stateful PCE
3.1. Passive Operations
3.2. Active Operations
3.3. PCE Initiation of LSPs
3.3.1. Per-Domain Stitched LSP
4. Security Considerations
5. Manageability Considerations
5.1. Control of Function and Policy
5.2. Information and Data Models
5.3. Liveness Detection and Monitoring
5.4. Verification of Correct Operations
5.5. Requirements on Other Protocols
5.6. Impact on Network Operations
5.7. Error Handling between PCEs
6. Other Considerations
6.1. Applicability to Interlayer Traffic Engineering
6.2. Scalability Considerations
6.3. Confidentiality
7. IANA Considerations
8. References
8.1. Normative References
8.2. Informative References
Acknowledgments
Contributors
Authors' Addresses
1. Introduction
1.1. Background
The Path Computation Element communication Protocol (PCEP) [RFC5440]
provides mechanisms for Path Computation Elements (PCEs) to perform
path computations in response to the requests of Path Computation
Clients (PCCs).
A stateful PCE is capable of considering, for the purposes of path
computation, not only the network state in terms of links and nodes
(referred to as the Traffic Engineering Database or TED) but also the
status of active services (previously computed paths, and currently
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